1. Field of the Invention
This invention relates, generally, to devices for use in automotive and other small engines that remove particles and volatiles from the oil used in such engines.
2. Description of the Prior Art
Theoretically, oil used to lubricate engine parts should last forever because the oil itself never breaks down. However, there are two sources of contamination that destroy the effectiveness of oil as a lubricant: abrasive particulate matter and volatiles such as moisture or uncombusted fuel. Accordingly, inventors have developed filter means for removing particulate matter and evaporator means for removing moisture and other volatiles that degrade the effectiveness of the oil.
Devices have also been developed that combine those two functions. For example, U.S. Pat. No. 4,189,351 to Engel shows a combination filter and evaporator unit. Oil to be filtered to remove particulate matter therefrom and to be heated in an evaporation chamber to remove volatiles therefrom is first introduced into a canister filled with filter material. After flowing through the filter material, the oil is introduced into an evaporator chamber where it is spread into a thin layer and heated to enhance its evaporation. A vent allows the evaporated volatiles to escape into the atmosphere.
There are two primary drawbacks to the above-described device. The evaporation is inefficiently performed because the heating element for supplying heat to the evaporation chamber is positioned in the closure means for the device and thus the heat of evaporation must be supplied through radiated heat, and the device is too large to fit under the hood of an automobile.
The inefficient heating problem was solved by a device shown in U.S. patent Ser. No. 07/667,949 to Menyhert, now U.S. Pat. No. 5,198,104. In that device, the heating element is placed in the evaporation plate where the heat is needed and the bulky, heat radiating lid of the Engle device is eliminated. However, said device is also too large to fit under the hood of an automobile. Moreover, the design of both earlier devices is such that changing of the filter material is somewhat difficult. More particularly, the filter media in both devices is positioned in a canister that is secured to the evaporation plate. Thus, at least partial disassembly of such devices is required when the filter media is replaced.
Thus, there remains a need for a combination filter and evaporator apparatus that is small enough for use in automotive and other small engine applications. Moreover, there is a need for a design that enables filter media replacement in the absence of unit disassembly. However, at the time the present invention was made, it was not obvious to those of ordinary skill in this art how those needs could be fulfilled, in view of the prior art as a whole.